For nearly a half century, articulated four-wheel drive vehicles have been widely used in the underground mining industry. This type of vehicle configuration is common for scoops, shield haulers and the like. The front section of such vehicles contains a driven axle and the particular attachment (scoop, fork, etc.) and the rear section houses the drive system for the vehicle, its hydraulics, controls, batteries and the like. To an extent, the vehicle is like a compact articulated front end loader commonly used in the construction industry, but with significantly reduced height.
As with all underground mining machinery, space is at a significant premium. The drive system of these vehicles normally consists of an electric motor with a pinion gear on its output shaft that plugs into a gearbox with a two stage helical gear parallel shaft reduction. The first stage is typically a fixed reduction to accommodate the motor pinion gear. The second stage reduction is tailored to accommodate the needs of different sizes and capacities of vehicles. The output shaft is typically double extended to both sides with universal joint flanges on each side. One side drives the front pair of wheels and the other side drives the rear wheels.
When this equipment was first designed, a disc was secured to one of the universal joint flanges and a mating caliper was secured to a built in pad on the gearbox to create a cost efficient dry caliper disc brake.
However, dry caliper disc brakes are generally not preferred in rigorous mining conditions and they have also lost favor due to changes in governmental regulations. Wet disc brakes then were adapted to fit the universal joint and the existing gearbox caliper pad. While these brakes performed much better than the dry caliper brakes, they were large, complicated in design, difficult to seal, difficult to replace, costly, and with a torque setting that typically required modification to accommodate different gear ratios. U.S. Pat. No. 6,260,668 is an attempt to resolve this problem, but in a significantly different manner than that presented herein.
There remains a need in the art for a wet brake and gearbox combination that will fit into the space accommodating the gearbox presently employed. It is most desirable that a wet brake be positionable between the motor and double extended output shaft of the gearboxes in issue. Heretofore, the art has been incapable of such packaging in a durable, reliable, and cost efficient manner.